Prevalence and an Analysis of Noise - Induced Hearing Loss in Army Helicopter Pilots and Aircraft Mechanics
Pariyanan Jaruchinda MD*, Taninsak Thongdeetae MD*, Suthee Panichkul MD, MSc**, Pongtep Hanchumpol MA*
Affiliation :
* Department of Otolaryngology, Phramongkutklao Hospital
** Department of Military and Community Medicine,
Phramongkutklao College of Medicine
Background and Objective : Hearing impairment from noise exposure has been reported in fix-wing pilots,
especially in civilized countries. However, there are few studies on rotary wing aviators and aircraft
mechanics, especially in developing countries whose hearing conservative program is not well established.
The present study, therefore, was done to evaluate the prevalence of noise induced hearing loss and the
contributing factors that may effect both groups of noise-exposed population.
Materials and Methods : Report questionnaires were reviewed and physical examination combined with
audiometric records of 34 pilots and 42 mechanics in the Royal Thai Army Aviation Center, Lobburi,
were examined. Hearing loss was studied using four categories of significant threshold shift (STS).
Amplitude of noise radiated by aircraft was also measured at different distances.
Results : No significant difference was found in prevalence of hearing loss in aviators (32.4%) and aircraft
mechanics (47.6%), but in the aircraft mechanics group there were more damage of frequency involvement
including speech frequency and high frequency and more decibels loss than aviators. The type of hearing
protection and smoking index were strongly correlated with hearing loss. Age, flight time and alcohol
habit had no significant effect and ninety percent of the subjects had no self awareness of hearing loss.
Conclusion : Aircraft mechanics had more severity on hearing loss than aviators. Types of noise protector
and cigarette smoking had significant association with hearing loss.
Keywords : Noise induced hearing loss, Helicopter pilots, Aircraft mechanics, Hearing protection, Cigarette smoking
